Resolution improvement for optical scanners

ABSTRACT

A device providing high resolution readout of information stored on a film. A slit equal in width to the desired spot size diameter is placed in front of a moving film. A fiber optics strip is placed in back of the film in line with the slit. A beam of light scans across the slit. The fiber optics strip is comprised of a plurality of optic fibers. The width of each fiber is also equal to the desired spot size diameter. All of the optic fibers are connected to a small group of photodetectors. The fibers and the detectors are arranged in such a manner that no one detector will receive information from more than one fiber at any one time as the beam scans across the slit.

United States ruwlu i 1 [1 ll 3,746,840 Ogland et al. July 17, 1973 [54]RESOLUTION IMPROVEMENT FOR 3,125,683 3/1964 Stewart et ill 250/227OPTICAL SCANNERS 3,371,324 2/l968 Sinoto 235/6l.l l5 3,l50,356 9/1964Newman 250/227 X [75] Inventors: Jon W. Ogland, Glen Burnie;

Edward Malarkey Sevema Park Primary Examiner-Thomas A. Robinson both ofAttorney-F. H. Henson, E. P. Klipfel and Stanley [73] Assignee:Westinghouse Electric Corporation, Weinberg Pittsburgh, Pa. 22 Filed:July 2, 1970 [57] ABSTRACT A device providing high resolution readout ofinforma- [21 1 Appl SL962 tion stored on a film. A slit equal in widthto the desired spot size diameter is placed in front of a moving film.52 CL 235 141 E, 250 227 350 9 B, A fiber optics strip is placed in backof the film in line 250/219 D with the slit. A beam of light scansacross the slit. The [51] Int. Cl. G03b 27/00, 006k 7/10 fiber opticsstrip is comprised of a plurality of Optic [58] Field of Search 235/6 l.11 E; bsrs- The width of each fiber is also equsll w the desired 50 2 29 1 227 17 73; 340 14 3 spot size diameter. All of the optic fibers areconnected to a small group of photodetectors. The fibers and the 5References Ci detectors are arranged in such a manner that no one UNITEDSTATES PATENTS detector will receive information from more than onefiber at any one. time as the beam scans across the slit 3,560,0852/1971 Sllverberg 350/96 B 3,384,755 5/1968 Williamson et al. 250/227 8Claims, 4 Drawing Figures 2 4 6 8 IO I2 I 3 5 9 ll I I3 l l l I l P l IL r 7 I"? I 1 r I H )(gxvx I\ 1Y\4\4\ l arses/i0 Patented July 17, 19733,746,840

LIGHT sounce INVENTORS Jon W. Oglond 6 Edward C. Molorkey.

ATTORNEY BY/WWLM RESOLUTION IMPROVEMENT FOR OPTICAL SCANNERS BACKGROUNDOF THE INVENTION cused, is limited by the divergence angle of' the laserbeam, 6, and the quality of the optical components of the system.Presently available lasers exhibit beam divergences of about 1milliradian. As a result, the mini mum spot size which can be achievedhas a radius of r 6f= 10 f, where fis the focal lengthof the focusinglens and r and f are measured in the same units. Since a minimumpractical focal length for the final lens in a scanning system is atleast from 2 to 10 cm, the minimum spot diameter achievable with a lasersource is 20 p, (micron). The problem up to now has been that highresolution photographic films are capable of resolutions of the order of5 p, and less. Hence lasers are not yet available which will allowextractions of all the information stored on the film.

BRIEF SUMMARY OF THE INVENTION The present invention increases theresolution capabilities in a scanner system which can use a beam oflaser light or a beam of incoherent light and allows readout of all theinformation stored on the film down to a spot size of the order of 5microns using the teachings of this invention, it is possible toset'resolution to a spot size of l to 2 microns. At the same time, itwill allow some relaxation of the requirements placed on the opticalcomponents of the system.

The invention described herein teaches an apparatus which provides highresolution of information in a first and second direction, theinformation being extracted from a moving film. Resolution in the firstdirection is provided by a narrow slit which is placed in front of thefilm that is, between the beam of scanning light and the film. Theheight of the slit is equal to the desired spot size diameter.

Resolution in the second direction is provided by a fiber optics stripcomprising a plurality of optically conductive fibers, which is placedon the other side of the film and in line with the slit. Therefore, whenthe slit is illuminated by the scanning beam, the fibers comprising thefiber optics strip are likewise, simultaneously illuminated. Each of thefibers in the fiber optics strip are of a width equal to the desiredspot size diameter.

Only a small number of photodetectors are connected to the fiberscomprising the fiber optics strip. Each of the fibers has first andsecond ends. The first ends of the fibers are divided into groups, eachgroup being at least equal to the width of the beam of light which isincident upon them. The fibers of each group are connected to thedetectors in a predetermined order. That is, the first fiber of aparticular group is connected to the first detector, the second fiber ofthe group is connected to the second detector and so on.

By requiring that the width of each group be equal at least to the widthof the scanning beam of light, each detector will receive a signal fromonly one fiber at any given time.

BRIEF DESCRIPTION OF THE DRAWINGS For a better understanding of theinvention, reference may be had to the preferred embodiment, exemplaryof the invention, shown in the accompanying drawings, in which:

FIG. 1 shows an exploded view of the film, the slit, the fiber opticsstrip, andthe scanning beam of light;

FIG. 2 is a block diagram of a preferred embodiment of the invention;

FIG. 3 shows an enlarged portion'of the fiber optics strip;

FIG. 4 shows a three-dimensionalview of the fiber optics strip and apreferredmanner of positioning its fibers relative to thephotodetectors.

DETAILED'DESCRIPTION OF THE INVENTION Referring to FIGS. 1 and '2, alight source 53 is shown illuminating a film 40 on which has beenrecorded certain information. In order to extract the information fromthe film, the film is moved by any well known means inthe directionindicated by arrow 42 past a scanning device indicatedgenerally at45.However, it will be recognized by those skilled'in'the art that the filmcould be moved in the opposite direction. Furthermore, it will also beapparent that the real requirement is relative movement between thefilm-40 and the scanning device 45. Therefore, the film 40 can bestationary and the scanning device 45 moved in a vertical direction.

Because many high resolution photographic filmsare capable ofresolutions of the order of 5 t, the scanning device 45 is designed toextract informationjof such small size and smaller sizes from" the film.Readout of such high resolution is obtained in a first or verticaldirection by placing an opaque mask 48 directly in front of the film. Aslit 50 is provided in the mask 48. The height H of the slit 50 is equalto the desired spot size diameter. If, for example, it is known that thefilm 40 will contain some information on the order of 5 p.,' the slit 50can be of a width of 5 a.

In orderto get resolution in a second or horizontal direction, the linedefined by slit 50 must be subdivided into elements of width equal tothe required spot size diameter. To accomplish high resolution readoutin the horizontal direction, a fiber optics strip 52 shown also in FIGS.3 and 4, is'placed directly behind the film and in line with the slit50.

The sensor strip 52 may consist of as many as 10,000 fibers of lightconducting material. The diameter or width of each fiber is equal to thedesired spot size diameter that is, it can be as small as 5 a or smallerdepending on the resolution of the information on the film and whetherit is desired to extract it. The height of each of the fibers is notimportant because any excess fiber material will be blocked out-by mask48. Therefore, the fibersneed only be the desired size in the horizontaldirection. The secondjor lower ends of each of the fibers of the fiberoptics'strip 52 are.cemented together to form a straight line. Thisstraight line of fibers is shown as a plurality of circles across slit50 in FIG. 1. The circles are shown by dashed lines because the fiberoptics strip 52 is on the back side of the film 40. In order to read outthe information contained on the film, a light beam 54 (which can besupplied by a laser or by'a source of incoherent light) is scannedacross the film at the level of the slit 50.

As the beam scans across the horizontal slit 50, the fibers, which arelocated on the other side of the film, are sequentially illuminated andtransmit the information on the film to a number of photodetectors whichare connected to the opposite loose ends of the fibers. Even though thebeam of light 54 illuminates many of the fibers at any one time, thisillumination does not decrease the resolution of the output because theresolution in the horizontal direction is determined solely by thediameter of each fiber.

If time and expense were not important factors, a separate detectorcould be connected to the loose ends of the fibers comprising the fiberoptics strip 52. However, because these are important factors, thenumber of detectors that are used is markedly decreased. In order to usea small number of detectors, it is determined how wide the scanninglight beam is in terms of fiber diameters. As an example, the width ofthe scanning beam is taken to be 10 fiber diameters as shown in FIG. 1.

As shown in FIG. 4, the first l fibers are taken as a group and are bentat various angles from vertical in order to identify more easily thevarious fibers comprising each group. It will be recognized that thegroup could consist of more than fibers. Each of the first, or looseends of the fibers 1 to 10 of the first group are connected to separatephotodetectors. Any well known photodetectors which are capable ofconverting light energy to electric energy can be used. For example,FIG. 4 shows sensor strips being used as the photodetectors. The sensorstrips can be connected to the fibers in any well known manner. Forexample, the sensor strips can be optically cemented to the fibers by acement which has the same optical index of refraction as the fibers.Accordingly, fiber l is connected to sensor strip 56, fiber 2 isconnected to sensor strip 58, fiber 3 is connected to sensor strip 60and so on until all 10 fibers of the first group of fibers of the fiberoptics strip have been connected to the 10 sensor strips.

' After the first l0 fibers of the fiber optics strip have beenconnected to their respective sensor strips, a second group of 10 fibers(fibers 11 through are bent out at various angles from vertical so thatthey too may be easily identified. Fiber 11 is then connected to sensorstrip 56, fiber 12 is connected to sensor strip 58, fiber 13 isconnected to sensor strip 60, and so on until all of the fibers 11 to20, have been connected to the appropriate sensor strips. This processis repeated continuously until all of the fibers in the fiber opticsstrip have been broken into groups of ten and each of the fibers in eachof the groups has been connected to the sensor strips in their order ofrotation.

Therefore, instead of using 10,000 detectors in the case where 10,000fibers are included in the fiber optics strip, only 10 detectors orsensor strips are needed to take care of 10 groups of fibers, each groupof which comprises I000 fibers. The 10 groups of fibers feed into the IQsensor strips which are sequentially energized by the fibers at a rateconsistent with the sweep rate of the light beam. As the beam sweepsalong the slit 50, only 10 fibers will be illuminated at any one timeand the output of only one fiber of a fiber group at a time will find anopen gate of the utilization means 55. As shown in FIG. 2, theutilization means 55 is connected to the output of the fiber opticsstrip 52. That is, utilization means 55 is connected to the outputs ofthe sensor strips. As an example, the utilization means 55 can be acomputer which is capable ofreading the signals detected by the sensorstrips. It can also be a transmitter which is capable of sending thesensor strip output signals to a receiver which will, in turn, analyzethe outputs. It can, in fact, be any device which is required to analyzeor reproduce the information detected by the sensor strips.

FIG. 1 shows the beam 54 illuminating fibers I through 10. The width Wof the beam 54 is equal to the width of any group of 10 fibers. As thebeam 54 scans to'the right, fiber 1 will no longer be illuminated; butfiber 11 will be illuminated. Therefore, even though fibers l and 11 areboth connected to sensor strip 56, sensor strip 56 will detect lightfrom only one of them at a time because when number 1 fiber isilluminated, number 11 is not and when number 11 is illuminated, number1 is not. Therefore, it is clear that, in the illustrated case, thegroup of fibers cannot be permitted to contain less than 10 fibers. Ifthey did contain less than 10 fibers, the scanning beam of light wouldoverlap adjacent groups of fibers too much, thereby causing at least onesensor to be energized by signals from more than one fiber at a time. Ofcourse, it is the job of the utilization means 55 which is connected tothe sensor strips to sort out the information and to determine whichfiber is energizing which sensor strip. However, if more than one signalcomes into a particular sensor strip at any one time, the electronicsystem cannot sep arate the superimposed signals and no usefulinformation is obtained.

A system has been shown, therefore, which greatly increases the spotsize resolution capability in a scanning beam system over that of thepresent day focused laser beams. The complexity of the opticalcomponents of the scanner system has been reduced because a much largerfinal beam diameter can be tolerated.

We claim as our invention:

1. A system for producing high resolution readout of informationcomprising a slit disposed directly across and coextensive with a sourceof information, said'slit providing a scanning aperture enablingscanningsaid of information in a first direction; means for causingrelative movement between said slit and said source of information; anoptical device disposed directly behind said source of information andin line with said slit for providing a readout in a second direction,said optical device including a plurality of optically conductive fibersarranged to form a plurality of groups, each of said groups beingcomposed of a predetermined number of said fibers, and a set ofdetectors connected to said groups of fibers, the number of detectorscomposing said set of detectors being equal to said predetermined numberof fibers which compose each group; and means for sweeping a beam oflight across said source of information through said slit and upon saiddevice for scanning in said second direction, the width of said beam oflight being equal to the width of any group of fibers.

2. The system of claim I wherein the width of said slit is equal to apredetermined spot size diameter.

3. The system of claim 2 wherein each of the fibers of the first groupis connected to a different detector of said set of detectors.

7. The system of claim 1 including a utilization means, said utilizationmeans being connected to said detectors.

8. The system of claim 6 wherein said plurality of optically conductivefibers are arranged in a straight line so as to be aligned with saidslit.

1. A system for producing high resolution readout of informationcomprising a slit disposed directly across and coextensive with a sourceof information, said slit providing a scanning aperture enablingscanning said of information in a first direction; means for causingrelative movement between said slit and said source of information; anoptical device disposed directly behind said source of information andin line with said slit for providing a readout in a second direction,said optical device including a plurality of optically conductive fibersarranged to form a plurality of groups, each of said groups beingcomposed of a predetermined number of said fibers, and a set ofdetectors connected to said groups of fibers, the number of detectorscomposing said set of detectors being equal to said predetermined numberof fibers which compose each group; and means for sweeping a beam oflight across said source of information through said slit and upon saiddevice for scanning in said second direction, the width of said beam oflight being equal to the width of any group of fibers.
 2. The system ofclaim 1 wherein the width of said slit is equal to a predetermined spotsize diameter.
 3. The system of claim 2 wherein each of the fibers ofthe first group is connected to a different detector of said set ofdetectors.
 4. The system of claim 3 wherein each of the fibers of saidfirst group is connected to said detectors in a predetermined order. 5.The system of claim 4 wherein the fibers in the remaining groups areconnected to said set of detectors in said predetermined order.
 6. Thesystem of claim 5 wherein the width of each fiber is equal to thedesired spot size diameter.
 7. The system of claim 1 including autilization means, said utilization means being connected to saiddetectors.
 8. The system of claim 6 wherein said plurality of opticallyconductive fibers are arranged in a straight line so as to be alignedwith said slit.